Recently I did a couple of open source contributions. I decided to document my learning here.

In this pull request I added Check for type coverage to travis CI for pyramid_heroku project.


The project explains itself as :

A bunch of helpers for successfully running Pyramid on Heroku

The Change

The code base already uses python type annotations, but it is not consistently applied thru out the project. The issue was created to ensure that every time CI runs, it checks for the type coverage, and fails if the coverage is below a certain threshold.

  • I “borrowed” the type_coverage script for another project.
  • I added couple of commands to the .travis.yml after successfully testing the commands locally.
  • I also needed to make some minor changes to the code for mypy to even finish.

What I learnt

This was the first time I “used” travis. .travis.yml seems easy. I had considered running travis locally, but on discussion, it was deemed “unnecessary”.

May be I should set it up locally sometime, just to understand the details.

I had only used “python 3 styled” type annotations in my past project, I learnt about : type annotations in the comments.

While the change itself was trivial, I learnt that the build fails on every “non-zero” exit value, for each command. This meant that even though everything seemed to working OK locally, my PR kept getting (auto) rejected, due to build failures

Since ideal goal is to have 100% type coverage, I started with that, till I realized that, that itself was making the build fail.

After discussion, I “lowered” the threshold to 15% (which was the existing coverage)

The Pull Request

For your reference, you can see the PR itself here